This invention relates to the recycling of scraps of single-ply synthetic plastic roof membranes of the type which are heat-seamable to form a one piece roof covering sized to fit the particular roof being covered. Such roofing membrances have found wide use in covering existing roofs as well as use in original roofs. Typically, the roof membranes are cut to size in a factory using measurements obtained at the building site and are then shipped to the building site in the form of elongate strips wound on rolls. At the building site, the edges of adjacent strips are seam welded to one another in a progressive manner and anchored to the roof deck. A considerable amount of scrap is generated at the factory during the cutting process to provide strips which will fit the roof deck being covered. While typically such scrap has been shipped to landfills for disposal, this method of disposing of the material has become ever more expensive and is not a satisfactory long term solution. There have been various proposals to recycle synthetic plastic material and the present applicant is aware of the following listed prior art patents:
______________________________________ 4,546,128 Nakajima 2,558,378 Petry 4,105,598 Stavrinou 3,531,562 Serrano et al 4,158,646 Benkowski et al 3,535,408 Ronden 4,250,222 Mavel et al 3,562,373 Logrippo 4,617,111 Grimm et al 3,806,562 Lamort et al 4,726,846 Jackson et al ______________________________________
Of the foregoing, U.S. Pat. No. 4,158,646 seeks to reclaim or reprocess thermoplastic sheet material with textile reinforcement. In this process the chopped scrap is delivered to a so-called cold mill wherein the gap is set to reduce the fiber to a minute size having lengths no greater than 0.250 inches so that the mixture can be calendered. The process requires low temperatures in the Banbury or other mill in order to achieve optimum rupturing and tearing of the fibers. While other fibers, including glass fibers and polyester fibers are mentioned in U.S. Pat. No. 4,158,646, the process was apparently concerned with vinyl coated cotton knit fabric. It is not believed that the process taught would be suitable for applicant's assignee's vinyl-enveloped polyester fabric and would not produce the tough, durable and extremely strong product which applicant's improved process produces.
In U.S. Pat. No. 4,546,128 chopped and crushed waste polyester or polyamide fibers, generated from sources such as sewing factories were admixed with virgin polypropylene resin to provide inexpensive composite materials and the process is clearly different than the process for treating roof membrane material which will be described.
The present applicant's assignee has also recycled some of the roofing material by cutting the material into small pieces, placing the pieces in a heated compression mold, and pressing the heated pieces together in a plastic state to form a pad which, upon cooling, is useful as a walk pad.